MICHEL EUGENE CHEVREUL. 455 



ture and use of soaps, oils, glycerine, and candles. Such familiar 

 words, as cholesterin, stearin, margarin, oleic acid, butyric acid, and 

 the like, have come down to us from Chevreul's work. It is safe to 

 say that, if the man had died iu his fortieth year, his name and fame 

 would still have been familiar to us. 



Subsequently to his work upon the fats, Chevreul occupied himself 

 with a great variety of chemical studies, and gave special attention to 

 matters relating to dyeing and painting. It was at this epoch that he 

 began his investigations of the laws of the h irmony of colors. His 

 book upon this subject, published in 1839, has been widely read, with 

 no little interest, by several generations of men. 



In studying the question of the harmony of colors, Chevreul was 

 impressed with the importance of having a definite standard with 

 which all colors could be compared, and by means of which all colors 

 could be accurately named. He argued that in the technical applica- 

 tion of colors, either for painting or dyeing, it is impossible to lay 

 dowu definite rules for obtaiuing a desired result unless each of the 

 colors to be employed can be accurately described. In order to do 

 this, he devised his so called chromatic circle, which was manifestly 

 a great improvement both upon the common practice of comparing 

 colors with natural objects, and upon the ideas of several scientific 

 men who have urged that definite standards of comparison might be 

 chosen among colored minerals, or birds, or flowers. This chromatic 

 circle well illustrates one peculiarity of Chevreul which was not a 

 little conspicuous ; namely, his leaning towards the methods of natu- 

 ralists. He sought always to classify ideas and substances into families, 

 genera, and species. He insisted on carefully distinguishing the chemi- 

 cal properties of bodies from their physical and organoleptic proper- 

 ties. To him the characteristic peculiarities of the " immediate 

 principles" (proximate constituents) in a compound were of deeper 

 interest than the question of their ultimate composition. 



For the fundamental ponts of comparison in his circle of colors he 

 chose from the solar spectrum definite rays of red, yellow, and blue, 

 the position of each of which was marked by that of certain stated 

 lines of Fraunhofer. These three colors were placed at equidistant 

 points on the circle, and between each pair of them were intercalated 

 twenty-three mixtures, so that the complete circle comprised seventy- 

 two colors in all. For example, half-way between yellow and blue 

 came green, and half-way between yellow and green came "yellow- 

 green." But between yellow and yellow-green were live different 

 tints, named yellow with green 1, or 2, or 3, or 4, or .0, respectively ; 



